public class 两数之和 {
    public int[] twoSum(int[] nums, int target) {
        Map<Integer,Integer> map = new HashMap<>();
        for (int i = 0;i < nums.length;i++) {
            if (map.containsKey(target - nums[i])) {
                return new int[]{i,map.get(target - nums[i])};
            }
            map.put(nums[i],i);
        }
        return null;
    }
}
